Process for producing knobs or the like



May 2, 1939.

F. B. WENDEL 2,157,044

PROCESS FOR PRODUCING KNOBS OR THE LIKE 3 Sheets-Sheet l Filed Feb. 24,1957 df f/ @YM May 2, 1939- F. B. wENDEL. y2,157,044

PROCESS FOR PRODUCING KNoBs 0R THE LIKE Filed Feb. 24, 193'? 3Sheets-Sheet 2 May 2, 1939 v F. B. wl-:NDEL 2,157,044

PaocEss Fon PRoDucING KNQBs 0R THE LIKE Filed Feb. 24. 1957 :ssheets-sheet 5 Patented May 2, 1939 PnocEss Fon PRonUorNG xNoBs on 'rnEFrans B. Wendel, Long Island City, N. Y.

Application February 24, 1937, Serial No. 127,458

10 Claims.

'Ihis invention relates to an improvement in processes for producinghollow bulbous objects from wrought metal, such for instance as doorknobs.

One of the objects of the present invention is to provide a superiormethod or process whereby bulbous objects may be economically producedfrom wrought metal.

A further object is to provide a superior process or method by means ofwhich bulbous wroughtmetal objects may be produced by a step involvingmarked lateral enlargement without occasioning the splitting ofthe saidenlargement.

Another object of the present invention is to provide a method wherebyhollow bulbous objects may be rapidly and accurately produced withoutoccasloning harmful marring of their surfaces.

With the above and other objects in view, as will appear to thoseskilled in the art from the present disclosure, this invention includesall features in the said disclosure which are novel over the prior artand which are not claimed by me in a separate application.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1 is a vertical central section through a die-block assemblyshowing a first-stage ,test-V tube-shaped blank installed therein priorto being subjected to a bulging operation;

Fig. 2 is a similar view showing the blank forced into the die-assemblyto produce a bulged secondstage blank;

Fig. 3 is a similar view illustrating the formation of a third-stageblank;

Fig. 4 is a similar View illustrating the formation of a fourth-stageblank;

Fig. 5 is a view looking toward the open end of the rst-stage blank;

Fig. 6 is a view partly in side elevation and partly in centrallongitudinal section of the rststage blank;

Fig. 7 is a similar view of the second-stage blank;

Fig. 8 is a bottom end view of the second-stage blank;

Fig. 9 is a view ofthe third-stage blank shown partly inside elevationand partly in 'central longitudinal section;

Fig. 10 is a view of the bottom end thereof ;v

Fig. 11 is a view of the fourth-stage blank shown partly in sideelevation and partly in central longitudinal section; and

Fig. 12 is a view looking toward the under end of the fourth-stageblank.

Various forms of dies may be employed in carrying out the presentprocess, and for purposes of illustration there is shown in Figs. 1 to 4in- 5 clusive a three-part die-assembly comprising two similarcomplementary die-blocks and 2|, respectively provided with verticalchannels 22 and 23 of semicircular form in cross-section, and togetherproviding a cylindrical passage for the rel0 ception of atest-tube-shaped wrought-metal blank 24 (Figs. 1, 5 and 6), which blankfor convenience of description may be designated as the mst-stage blank.The said rst-stage blank may be produced from wrought-metal, such, for uinstance, as copper or steel, by drawing or other operations, in amanner well known in the art.

Preferably, and as shown especially well in Fig. 6, the exterior of therst-stage blank 24 is of straight cylindrical form save at its closedend 25, which is of hemispherical form as shown. 'I'he wall of thehollow first-stage blank 24 is preferably formed of uniform thicknessthroughout the zone marked A in Fig. 6, and from the lower terminus ofthis zone A the wall thickness progressively increases toward thespherically-contoured closed end at the center 25 of which it reachesits maximum thickness.

The die-blocks 20 and 2 I, before referred to, are arranged incooperative relationship with a third die-block 26, with respect towhich latter they are movable to permit the introduction and removal ofvarious blanks of the character as will hereinafterappear. 'I'he innerends of the semicylindrical channels 22 and 23 formed respectively inthe die-blocks 20 and 2| merge into enlarged semiannular portions 21 and28, which together with an upwardly-opening annular recess 29 in theupper face of the die-block 26 provide a cavity conforming in shape tothe desired bulbous form of the portion of the object to be produced,which in the instance being described is a hollow door knob.

.Leading downwardly from the central portion of the upwardly-openingrecess 29 in the dieblock 26 is a cylindrical socket 30 which is adaptedto interchangeably receive a deflectingblock 3| of the character shownin Figs. 1 to 3 inclusive, or a filler-block 32 of the character shownin Fig. 4. For the purpose of 'securing the blocks 3| and 32 in place,each thereof is provided with a threaded bore 33 having threaded into itthe upper end of a retaining-bolt 34 extending upwardly through thedie-block 26.

After the die-blocks 2U, 2| and 26 have been 55 assembled and rmlyclamped together the testtube-shaped first-stage blank 24 is filled withwater, oil or other suitable medium and is introduced into the verticalpassage formed by the registering semicylindrical channels 22 and 23untilits lower end rests against the defiectingblock 3|.

A plunger 36 is now forced downwardly into the first-stage blank 24 by atoggle press or other suitable means for imparting a powerful thrustupon the said plunger and force the same toward the deilecting-block 3|.The plunger 36 is provided with an L-shaped relief-passage 31 whichopens at one end through the sphericallycontoured lower end of the saidplunger and opens at its opposite end through the periphery ofthe saidplunger at a predetermined point below a thrust-shoulder 38 formed uponthe latter.

During the first portion of the downward stroke of the plunger 36 aportion of the liquid contained in the blank 24 will be expelled throughthe relief-passage 31 due to displacement caused by the said plunger.When however the upper end of the relief-passage 31 passes by the upperedge of the blank 24 the further escape of liquid will be substantiallyprevented by the sealing action of the wall of the blank. 'Ihe continueddownward movement of the plunger will cause a hydraulic pressure withinthe lower portion of the blank 24 with the result that the same will bebulged outwardly by this pressure into substantially the form shown bythe broken lines 39 in Fig. 1 before the thrust-shoulder 38 contacts theupper edge of the blank. When during the downward stroke of the plungerits thrust-shoulder 38 engages with the upper edge of the blank as justreferred to, the said shoulder will force the said blank downwardly sothat the lower portion thereof will ultimately assume substantially theform of the second-stage blank 40 shown in Figs. 2, 7 and 8. In thisconnection it will be appreciated that the uid or other suitable mediumwithin the first-stage blank 24 will serve to prevent the same fromcollapsing under the thrust of the plunger 36 and will compel the blankto bulge outwardly and downwardly as illustrated in Figs. 2, 7 and 8before referred to. During the operation above described thedefiecting-block 3| will act to cause the bottom end wall 4 of the blankto assume a concavo-convex form, thus producing in the end of the blanka spherically-contoured recess 42.

The plunger 36 is now lifted clear of the second-stage blank and thedie-blocks 20, 2| and 26 are separated to permit the removal of the saidblank 40 which latter after being emptied of residual fluid may besubjected to an annealing operation to soften the same and relieve it ofthe hardness and cold-working strains occasioned by the formingoperation before described. The annealing temperature and the length oftime to which the blank is subjected to such temperature in order toachieve the desired softening action will vary widely depending upon thematerial from which the blanks are formed and other circumstances fullyunderstood by those skilled in the art of metal working.

After the second-stage blank has been annealed it is again filled withliquid and is held in position between the die-blocks 20, 2| and 26which latter are now closed and clamped together preparatory toconverting the secondstage blank into a third-stage blank as will bepresently described.

'I'he second-stage blank is now subjected to the action of a plunger 43(Fig. 3) which substantially corresponds to the plunger 36 beforereferred to save that its thrust-shoulder 44 is slightly closer itsrounded lower end. Like the plunger 36 the plunger 43 is provided withanv L-shaped relief-passage 45 which as the plunger descends has itslateral terminal sealed by the inner surface of the blank before itsthrustshoulder 44 engages the outer edge thereof. In this manner theblank is subjected to a relativelyslight hydraulic bulging action beforethe thrustshoulder engages the outer edge of the blank to forcibly movethe tubular portion of the said blank downwardly toward thedeflecting-block 3 At the conclusion of the downward stroke of theplunger 43 the blank will assume substantially the shape shown in Figs.3, 9 and 10 and may therefore be designated for convenienceofdescription as a third-stage blank 46. The thirdstage blank owingtothe presence of the deecting-block 3| will have its end wall 4| moredeeply impressed to provide a spherically-contoured recess 41.

The plunger 43 is now withdrawn from the blank and the die-blocks 20, 2|and 26 are separated to permit the removal of the third-stage blank 46which latter after being emptied of residual fluid will be subjected toan annealing operation.

After the third-stage blank has been softened and again filled withliquid it is inserted between the die-blocks and the latter are againclosed and rmly clamped together. Prior to the closing of the die-blocksthe deflecting-block 3| will have been removed from the socket 30 vinthe die-block 26 and the filler-block 32 substituted therefor. Thisfiller-block 32 just referred to instead of projecting into the diecavity, as did the deecting-block 3|, has a concaved upper surfaceshaped to complement and symmetrically continue the curvature of the diecavity 29.

In effecting the formationfof the fourth-stage fore described save thatthe'distance 'from its thrust-shoulder 50 to its rounded lower end issomewhat shorter and 4preferably the laterallyextending upper end of itsL-shaped relief-passage 5| is located a greater distance from the saidthrust-shoulder 50. By this means the plunger 49 subjects the blank to agreater khydraulic pressure than occurs during the preceding stages,before the thrust-shoulder 50 engages the upper edge of the blank.

This hydraulic pressure serves to force the end Wall 4|b of thethird-stage blank downwardly into the continuous symmetrical form 4|shown in Figs. 4, 11 and l2 and, coupled with a relatively slight endthrust exerted upon the blank by the thrust-shoulder 50 of the plunger49, to cause the metal of the blank to be deflected outwardly into anannular groove 52l half of which is formed in each of the die-blocks 2|)and 2|. This deilection of the metal into the annular groove 52 servesto provide the fourth-stalle blank with an annular bead 53.

Ihe fourth-stage blank may be considered as a finished door knob savefor being subjected to desired polishing operations and such machiningoperations upon its tubular shank 54 as will provide for the coupling ofthe same to a spindle or whatever other device is desired.

The number of operations necessary to convert the test-tube-shapedfirst-stage blank 24 of Figs. 5 and 6 into the blank shown in Figs. 11and 12 may vary widely depending upon the ductility of the wrought metalemployed and other factors obvious to those skilled in the art.

From the foregoing it will be seen that in producing hollow bulbousarticles they are deliberately deformed prior to final shaping since ithas been found that by means of this step the rupturing of the blank isavoided and rapidity of production greatly accelerated. As before notedthe first-stage blank preferably has its wall ta.- pered from the zone Adownwardly to the point 25 so as to provide an extra thickness of metalat a location where the greatest degree of stretching is apt to occur.

It may further be noted that by first producing the deformation, suchfor instance as the concavo-convex portion 41, on the partly-iinishedbulbous article and then re-forming such deformation into the desiredfinished contour, it is possible without undue and costly manufacturingprecautions to provide suilicient metal at a point remote from thetubular shank of the partly-finished bulbous article to insure thedesired nished contour. This will be apparent when it is realized thatby re-forming the deformation at a point remote from the initial sourceof metal (the tubular neck-portion of the blank) the adjacent metal isin effect compressed radially so that the metal is caused to seat itselfwholly against all of the interior shapes of the die-cavity withoutdanger of rupturing the metal, as might be the case if the metal wereforced to final shape by hydraulic stretching.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

1. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofand submitting a portion thereof to constraining-action constraining thesaid portion from expanding during the said application ofexpanding-force, to partially form a bulbouscontour to whichstretching-strains of the metal are then substantially confined, and toform an offset thereto comprised of the constrained portion; andsubsequently reshaping the said constrained portion to complete the saidbulbouscontour; whereby in forming a bulbous enlargementstretching-strains are isolated in portions thereof and rupture loss issubstantially eliminated.

2. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofand submitting a portion thereof to constraining-action constraining thesaid portion from expanding during the said application ofexpanding-force, to partially form a bulbouscontour to whichstretching-strains of the metal are then substantially confined, and toform an offset thereto comprised of the constrained portion, theconstrained offset portion being-concavo-convexly curved with respect toan adjacent portion of bulbous-contour; and subsequently reshaping thesaid concavo-convexly constrained portion to complete the saidbulbouscontour; whereby in forming a bulbous enlargementstretching-strains are isolated in portions thereof and rupture loss issubstantially eliminated. I 1

3. A process for producing a hollow bulbo object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially of the axis thereof and submitting aportion of the closed end-wall to constraining-action constraining thesaid portion of the closed end-wall from expanding during the saidapplication of expandingforce, to partially form a bulbous-contour towhich stretching-strains of the metal are then substantially conned, andto form an offset thereto comprised of the constrained portion of thesaid closed end-wall; and subsequently reshaping the said constrainedportion to complete the said bulbous-contour; whereby in forming abulbous enlargement stretching-strains are isolated in portions thereofand rupture loss is substantially eliminated.

4. A process for producing a hollow bulbous object comprising: applyingexpanding-form to a metal blank of tubular form at a closed end thereofto expand -the said blank radially and axially and submitting a portionof the closed end-wall to constraining-action constraining the saidportion of the closed end-wall from expanding during the saidapplication of expandingforce, to partially form a bulbous-contour towhich stretching-strains of the metal are then substantially confined,and to form an offset thereto comprised of the constrained portion ofthe said closed end-wall; and subsequently reshaping the saidconstrained portion to complete the said bulbous-contour; whereby informing a bulbous enlargement stretching-strains are isolated inportions thereof and rupture loss is substantially eliminated.

5. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially of the axis thereof and submitting aportion of the closed end-wall toconstraining-action constraining thesaid portion of the closed end-wall from expanding during the saidapplication of expandingforce, to partially form a bulbous-contourA towhich stretching-strains of the metal are then substantially confined,and to form an o'set thereto comprised of the constrained portion of thesaid closed end-wall, the said offset portion being concavo-convexlycurved; and subsequently reshaping the said concavo-convexly constrainedportion to complete the said bulbous-contour; whereby in forming avbulbous enlargement stretching-strains are isolated in portions thereofand rupture loss is substantially eliminated.

6. A. process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially and axially and submitting a portion of theclosed end-wall to constraining-action constraining the said portion ofthe closed end-wall from expanding during the said application ofexpanding-force, to partially form a bulbous-contour to whichstretching-strains of the metal are then substantially confined, and toform an offset thereto comprised of the constrained portion of the saidclosed end-wall, the said offset portion being concave-convexly curvedwith respect to an adjacent portion of the closed end-wall ofbulbouscontour; and subsequently reshaping the said concavo-convexlyconstrained portion to complete the said bulbous-contour; whereby informing a bulbous enlargement stretching-strains are isolated inportions thereof and rupture loss is substantially eliminated.

'7. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially of the axis thereof and submitting aportion of the closed end-wall to constraining-action constraining thesaid portion of the closed end-wall from expanding during the saidapplication of expanding-force, to partially form a bulbous-contour towhich stretching-strains of the metal are then substantially confined,and to form an offset thereto comprised of the constrained portion ofthe said closed end-Wall, the said offset portion being concavo-convexlycurved and offsetting toward an open end of the blank; and subsequentlyreshaping the said concave-convexly constrained portion in the directionaway from the `said open end of the blank to complete the saidbulbouscontour; whereby in forming a bulbousenlargementstretching-strains are isolated in portions thereof and rupture loss issubstantially eliminated.

8. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially and axially and submitting a portion of theclosed end-Wall to constraining-action constraining the said portion ofthe closed end-wall from expanding during the said application ofexpanding-force, to partially form a bulbous-contour to whichstretching-strains of the metal are then substantially confined, and toform an offset thereto comprised of the constrained portion of the saidclosed end-wall, the said offset portion being concavo-convexly curvedwith respect to an adjacent portion of the closed end-wall ofbulbouscontour, and offsetting toward an open end of the blank; andsubsequently reshaping the said concavo-convexly constrained portion inthe direction away from the said open end of the blank to complete thesaid bulbous-contour; whereby in forming a bulbous enlargementstretching-strains are isolated in portions thereof and the rupture lossis substantially eliminated.

9. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially of the axis thereof and submitting aportion of the closed end-wall thereof to constraining-actionconstraining the said portion of the closed end-wall from expandingduring the said application of expanding-force, to partially form abulbouscontour to which stretching-strains of the metal are thensubstantially confined, and to form an offset thereto comprised of theconstrained portion of the said closed end-wall, the said offset portionbeing concavo-convexly curved and offsetting toward an open end of theblank; and subsequently curving the said concavo-convexly constrainedportion in the direction away from the said open end of the blank tocomplete the said bulbous-contour; whereby in forming a bulbousenlargement stretching-strains are isolated in portions thereof andrupture loss is substantially eliminated.

10. A process for producing a hollow bulbous object comprising: applyingexpanding-force to a metal blank of tubular form at a closed end thereofto expand the blank radially and axially and submitting a portion of theclosed end-wall to constraining-action constraining the said portion ofthe closed end-wall from expanding during the said application ofexpanding-force, to partially form a bulbous-contour to whichstretching-strains of the metal are then substantially conflned, and toform an offset thereto comprised of the constrained portion of the saidclosed end-wall, the said offset portion being concave-convexly curvedwith respect to an ad' jacent portion of the closed end-wall ofbulbouscontour, and offsetting toward an open end of the blank; andsubsequently curving the said concavo-convexly constrained portion inthe direction away from the said open end of the blank to complete thesaid bulbous-contour; whereby in forming a bulbous enlargementstretchingstrains are isolated in portions thereof and the rupture lossis substantially eliminated.

FRANS B. WENDEL.

